Papers by Keyword: Crevice Corrosion

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Authors: Ping Zhao, Jia Xing Yang, Peng Peng Zhu, Cheng Sun, Jin Xu
Abstract: The effect of sulfate reducing bacteria (SRB) on the corrosion of Q235 steel has been investigated in the crevice under the simulated disbonded coating with aperture width of 1.0 and 0.5mm in the soil-extract solutions (SES) by using electrochemical methods. The results show that the existence of SRB in SES can cause corrosion potential of the working electrode to shift to a more negative value, and the formation of pitting on the surface of the electrode. Compared with the crevice width of 1.0mm, the corrosion potential of the electrode shows a little more positive at the crevice width of 0.5mm. The corrosion rate of the electrode increases with the increase of aperture width in the SES without SRB, however, decreases with the increase of aperture width in the SES with SRB. The results obtained indicate that either bio-film on the surface of the electrode formed by SRB in SES or aperture width has obvious influences on the crevice corrosion process of the carbon steel.
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Authors: T. Sundararajan, Eiji Akiyama, Kaneaki Tsuzaki
Abstract: Crevice corrosion experiments on pure iron were carried out in a 0.5 M acetate buffer with varied chloride concentrations. Changes in resultant currents and morphology due to crevice attack were explained by IR potential drop mechanisms. The specimens experienced potential drop inside the crevice, which resulted in the formation of passive, active, and hydrogen evolution regions. The passive region did not exist in the electrolyte containing 0.05 M and 0.5 M chloride. Hydrogen evolution, which occurred inside the crevice was measured on rear side of the specimen using hydrogen permeation test. The results suggest that the hydrogen produced inside the crevice is measurable using a permeation test. The entry of diffusible hydrogen showed a significant increase with the addition of chloride into the acetate buffer.
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Authors: Zhi Ming Shi, Andrej Atrens
Abstract: Plug-in specimens enable measurement of reliable Mg polarization curves. Cathodic polarization curves were measured for high purity Mg in 3.5% NaCl saturated with Mg(OH)2 using (i) mounted specimens and (ii) plug-in specimens. Polarization curves yielded the corrosion current density icorr and the corresponding corrosion rate Pi, which was compared with corrosion rates evaluated from hydrogen evolution, PH, and weight loss, PW. Mounted specimens produce Pi values three times larger than plug-in specimens, due to crevice corrosion in the mounted specimens. Plug-in specimens had no crevice and allow simultaneous measurement of PH and Pi. Pi was less than PH and indicated an apparent valence of 1.45 in support of the existence of the uni-positive Mg+ ion.
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Authors: Hannu Hänninen
479
Authors: Qian Hu, Jing Liu, Jie Zhang, Feng Huang, Xing Peng Guo
Abstract: The crevice corrosion behaviors of X52 carbon steel in two typical Cl--containing solutions were investigated by electrochemical noise and electrochemical impedance spectroscopy. Results show that oxygen concentration difference leads to the coupled current in NaCl + NaHCO3 solution while HAc concentration difference causes the coupled current in NaCl solution saturated with CO2 in the presence of HAc. There exists an apparent incubation stage during the crevice corrosion process of X52 carbon steel in the former. However, no obvious incubation period of crevice corrosion can be observed in the latter. Micrography shows that the crevice corrosion occurs indeed and the corrosion inside the crevice is not uniform.
1432
Authors: Pornsak Srisungsitthisunti, Siriporn Daopiset, Noparat Kanjanaprayut
Abstract: Crevice corrosions of duplex stainless steels were investigated under the aggressive condition of sea water pumps in offshore petroleum platforms. The study aims to compare crevice corrosion behavior of three grades of duplex stainless steels, UNS S32101 (2101), UNS S31803 (2205) and UNS S32750, in seawater with 200 ppm of hypochlorite. Duplex steels were compared with a widely used austenitic steel UNS S31603 (316). Specimens were tested under synthetic sea water prepared at pH4, pH6 and pH8 by the cyclic potentiodynamics polarization technique and the potentiostatic technique. The results show that the duplex stainless steels had higher corrosion resistance compared with the 316. The released charges and the corrosion rates of the 2101 and the 2205 were similar, but much lower than those of the 2507especially after 3 months period.
123
Authors: Li Bin Niu, Katsuyuki Kobayashi
Abstract: Crevice corrosion of 3.5NiCrMoV and 13Cr steels, which are used as low-pressure (LP) steam turbine materials, was investigated by electrochemical corrosion tests in the simulated boiler water contained chloride and sulfate ions. For 3.5NiCrMoV steel, by comparison with the surfaces outside crevice, the surfaces inside crevice of the specimens coupled with both of the same steel and 13Cr steel showed no remarkably corroded pattern even though pitting corrosion was observed. The specimen of 13Cr steel coupled with the same steel plate exhibited pitting corrosion inside the crevice, and a lower open cycle potential (Ocp) than the single plate of 13Cr steel. On the other hand, the specimen of 13Cr steel coupled with 3.5NiCrMoV steel plate showed the lowest Ocp, as the anodic dissolutions of 3.5NiCrMoV steel became the dominate corrosion mechanism.
192
Authors: Laura L. Machuca, Stuart I. Bailey, Rolf Gubner
Abstract: Crevice corrosion (CC) was investigated for a number of selected corrosion resistant alloys in natural seawater containing microorganisms for up to 18 months under stagnant conditions. Experimental controls consisted of tests in natural seawater filtered in accordance with hydrostatic testing procedures. The corrosion potential of alloys was monitored throughout exposure and corrosion was evaluated by weight loss and 3D optical microscopy. CC was initiated on several alloys and corrosion rates in time indicated a positive effect of seawater filtration on the long-term performance of the alloys. Microbial adhesion, as indicated by fluorescence microscopy, occurred mainly outside the crevice and differed according to the nature of the substratum surface.
276
Authors: Woon Suk Hwang, Seung Chan Na, Jeong Ja Lee
Abstract: In order to investigate the corrosion behavior of TiNi shape memory alloy, especially electrochemical behavior of pitting and crevice corrosion in a human body, current density contour(CDC) map of TiNi alloy was constructed by potentiodynamic polarization technique in simulated physiological sodium chloride solutions of pH ranging from 1 to 13 at 37oC. Morphology of pits and corrosion products in sodium chloride solutions of various pH were analyzed by SEM and EDX, and susceptibility and mechanism of localized corrosion were also discussed.
573
Authors: Yasuyuki Katada
Abstract: Nitrogen evolution research has been widely carried out in Japan after the Forth International Conference on High Nitrogen Steels held in 1995 in Kyoto (HNS1995). The first research forum on nitrogen evolution research has been started in The Japan Society of Corrosion Engineering in 1996, followed by a series of research forums in the Iron and Steel Institute of Japan (ISIJ). In the meantime, a pressurized electro-slag remelting furnace was newly developed in National Institute for Material Science in 1998. A new research group regarding the availability of nitrogen on the improvement in steel properties has been started in ISIJ in 2004. Current research activities of the group cover the fabrication of HNS such as mechanical alloying, pressurized ESR and nitrogen absorption, evaluation technologies of HNS such as microstructure and precipitation behavior of nitride, mechanical properties, corrosion properties and physical properties, joining/welding technologies. As one of the applications of HNS, Ni-free high nitrogen steels with high strength, anti-corrosion, non-magnetic properties are very attractive in the fields of bio/medical ones as anti-Ni allergy material. Recent research activities including some topics mentioned above will be discussed.
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